Effect of metformin on myocardial cell apoptosis induced by hypoxia/reoxygenation injury

Objective: To investigate the effect and underlying mechanism of metformin on myocardial cell apoptosis induced by myocardial ischemia-reperfusion injury in rats. Methods: Forty suckling Wistar rats were selected, and the hearts were removed under aseptic condition. Rat myocardial cells were primarily cultured to establish hypoxia/reoxygenation injury (H/R) models of myocardial cells in vitro and the models were randomly classified into four groups: blank control group, metformin group, H/R group and metformin + H/R group. The apoptotic rate of primary rat myocardial cells in each group was tested with the terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. The cell counting kit-8 (CCK-8) assay was utilized to measure the viability of primary rat myocardial cells in each group. The relative expression of HIF-1 alpha mRNA of primary rat myocardial cells in each group was assessed by using real-time PCR. The relative expression of Bcl-2 and Bax protein of primary rat myocardial cells in each group was tested by using Western Blot assay. Results: As compared with the blank control group, the apoptotic rate of primary rat myocardial cells in the H/R group was significantly increased (P<0.001) and the cell viability was obviously reduced (P<0.001). When compared with hypoxia and reoxygenation culture, metformin pretreatment significantly reduced the apoptotic rate of myocardial cells (P<0.001) and promoted cell survival in rats (P<0.001). Meanwhile, real-time PCR results showed that the relative expression of HIF-1 alpha mRNA was significantly decreased in the metformin + H/R group. Western Blot results showed that the relative expression of Bcl-2 protein was significantly increased and relative expression of Bax protein was significantly decreased in the metformin + H/R group, with statistical differences. Conclusion: Metformin can reduce the apoptosis of rat myocardial cells following ischemia-reperfusion injury. The underlying mechanism may be associated with an improvement in cell viability, suppression in HIF-1 alpha expression, increase in the apoptosis inhibitor Bcl-2e expression and decrease in the Bax expression.